Role of DNMT3a expression and nuclear translocation under ELAVL1 mediation for dendritic cell function and Th17/Treg balance in COPD

Background

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. The DNA methyltransferase DNMT3a has been implicated in COPD, however its upstream regulation and downstream mechanisms remain unclear.

Methods

Relative mRNA and protein levels of indicated genes in lung tissues and dendritic cells (DCs) were tested via qRT-PCR and western blot, respectively. Cellular distribution of DNMT3a in DCs was determined by immunofluorescence staining. COPD mouse model was established by exposing mice to cigarette smoke (CS) via nose. The Th17/Treg cell ratio was examined using flow cytometry. Production of indicated cytokines was assessed by corresponding commercial ELISA kit. Interplay between DACH1 and c-Jun was verified by Co-immunoprecipitation, ChIP and luciferase reporter assays. Methylation level of DACH1 was tested by methylation specific PCR.

Results

DNMT3a expression was upregulated and negatively correlated with lung function in COPD patients. CS exposure increased pulmonary DNMT3a in mice. DNMT3a was predominantly expressed in the nucleus and CS exposure promoted its translocation to cytoplasm. RNA binding protein ELAVL1 upregulated DNMT3a expression, induced its nuclear translocation and increased its enzyme activity. DNMT3a promoted Th17 differentiation while inhibited Treg differentiation. DNMT3a methylated DACH1 and inhibited its expression, resulting in c-Jun pathway activation. In vivo DNMT3a knockdown ameliorated lung injury and Th17/Treg imbalance in COPD mice.

Conclusion

This study suggests that ELAVL1 regulates DNMT3a expression and nuclear translocation to modulate dendritic cell function and Th17/Treg balance through DACH1/c-Jun pathway in COPD.